In terrestrial zoology, megafauna (Ancient Greek megas "large" + New Latin fauna "animal") are large or giant animals. The most common thresholds used are 45 kilograms (100 lb) or 100 kilograms (220 lb). This thus includes many species not popularly thought of as overly large, such as white-tailed deer and red kangaroo, and even humans.
In practice, the most common usage encountered in academic and popular writing describes land animals roughly larger than a human that are not (solely) domesticated. The term is especially associated with the Pleistocene megafauna — the land animals often larger than modern counterparts considered archetypical of the last ice age, such as mammoths, the majority of which in the Americas and Australia became extinct fairly recently (10,000-40,000 years ago). It is also commonly used for the largest extant wild land animals, especially elephants, giraffes, hippopotamuses, rhinoceroses, and large bovines. Megafauna may be subcategorized by their trophic position into megaherbivores (e.g. elk), megacarnivores (e.g. lions), and more rarely, megaomnivores (e.g. bears).
The brown bear (Ursus arctos) is a large bear distributed across much of northern Eurasia and North America. Adult bears generally weigh between 100 and 635 kg (220 and 1,400 lb) and its largest subspecies, the Kodiak bear, rivals the polar bear as the largest member of the bear family and as the largest land-based predator. There are several recognized subspecies within the brown bear species. In North America, two types are generally recognized, the coastal brown bear and the inland grizzly bear, and the two types could broadly define all brown bear subspecies. An adult grizzly living inland in Yukon may weigh as little as 80 kg (180 lb), while an adult brown bear in nearby coastal Alaska living on a steady, nutritious diet of spawning salmon may weigh as much as 680 kg (1,500 lb). The exact number of overall brown subspecies remains in debate.
While the brown bear's range has shrunk and it has faced local extinctions, it remains listed as a least concern species by the IUCN with a total population of approximately 200,000. As of 2012, this and the American black bear are the only bear species not classified as threatened by the IUCN. However, the Californian, North African (Atlas bear), and Mexican subspecies were hunted to extinction in the nineteenth and twentieth centuries and the Marsican brown bear in central Italy is believed to have a population of just 30 to 40 bears.